The invention relates to truck trailers, especially the structural beams that are used to form the roof of a truck trailer. Such beams must be strong, but lightweight, since weight is a critical factor in the transportation of goods over highways. For this reason, the sidewalls and roof of a truck trailer are normally built of aluminum, or some other lightweight material.
The invention is designed to maximize the strength of the roof beams while minimizing the material from which they are formed.
Briefly stated, the invention is in a method of extruding a U-shaped beam which has a flat web that is straight between opposing ends of the beam, and a pair legs which extend at least initially in parallel relation from the web which is thicker than the legs. The extruded beam is then placed in a press where the free ends of the legs are bent outwardly to form in the upper surface of the beam, a bow or crown which curves outwardly away from the straight web.
The combination extrusion and bending process produces a beam with optimum strength at minimal costs. This is very important when you consider the millions of beams that are used in the production of truck trailers.